Why do we say “You made your bed”?

The picture is simple: whoever makes a lumpy bed is the one who has to sleep in it. Anthony Trollope used it in his 1860–61 novel Framley Parsonage, where a man “had made his own bed” and must lie upon it. Not everyone agreed. In 1919, Somerset Maugham called it “one of the falsest of proverbs.”